Field of the Invention
The invention lies in the field of interior cleaning of receptacles and relates to a device and to a method for removing deposits in the interior of receptacles by way of blasting technology. In particular, the invention relates to a device and to a method for cleaning dirty and slagged receptacles with caking on their inner walls, in particular of incineration installations, by way of blasting technology. Such a method is also called blasting cleaning.
Description of Related Art
Heating surfaces, e.g. of waste incineration plants or coal-fired boilers are generally exposed to large contamination or fouling. This fouling has inorganic compositions and typically arises due to deposits of ash particles on the wall. Coatings in the region of high flue gas temperatures are mostly very hard, since they remain stuck to the wall in either molten form or are melted on the wall or are stuck together by way of substances melting or condensing at a lower temperature, when solidifying on the colder boiler wall. Such coatings are very difficult to remove and are inadequately removed by way of known cleaning methods. This leads to the boiler having to be being periodically taken out of service, cooled and cleaned manually or by way of sand blasting. For this, the construction of a scaffold in the furnace or kiln is often necessary, since such boilers usually have extremely large dimensions. This moreover requires an operational interruption of several days or weeks and is extremely unpleasant and unhealthy for the cleaning personnel due to the large occurrence of dust and dirt. One consequence which mostly inherently occurs with an operational interruption of an installation is damage to the container materials themselves as a result of the large temperature changes. The installation standstill costs due to the production or income losses are an important cost factor, additionally to the cleaning and repair costs.
Conventional cleaning methods that are used when the installations are shut down are for example boiler beating, as well as the use of steam jet blasters, water jet blasters/soot blasters as well as sand blasting.
Moreover, a cleaning method is known, with which the cooled-down or the hot boiler that is in operation is cleaned by way of introducing and igniting explosive bodies. The disadvantage with this method is the necessity for explosives. Apart from the high costs for the explosive material, a huge expense with regard to safety must be met, for example with the storage of the explosive, in order to avoid accidents and theft. The introduction of explosive material into a hot receptacle moreover necessitates an absolutely reliable and efficient cooling system, in order to prevent a premature detonation of the explosive.
A further cleaning method is known from EP 1 362 213 B1, which likewise makes use of means for the production of an explosion. Instead of explosive, according to this method however, a container envelope that is inflatable with an explosive gas mixture is attached onto the end of a cleaning lance. The cleaning lance then together with the empty container envelope is introduced into the boiler space and is positioned in the proximity of the location to be cleaned. Subsequently, the container envelope is inflated with an explosive gas mixture. An explosion is produced by way of igniting the gas mixture in the container envelope, and the shock waves of this explosion lead to the detachment of fouling on the boiler walls. The container envelope is thereby shredded and combusted by way of the explosion. It therefore represents a consumable material.
This method and the associated device compared to the blasting technology with explosive and which is mentioned above, has the advantage that the method is favourable with regard to operation. Thus, for example, the starting components of a gas mixture, which comprises oxygen and a gas of the group of combustible hydrocarbons, is inexpensive in procurement in comparison to explosives. Moreover, the procurement and handling of the mentioned gases, in contrast to explosives requires no special permits or qualifications, so that anyone with a suitable training can carry out the method. Moreover, it is also advantageous that the starting components are fed to the cleaning lance via separate feed conduits or are even introduced separately into the receiving space of the container envelope, and the dangerous explosive gas mixture therefore is not created in the cleaning lance or even in the receiving space of the container envelope already placed in the boiler space, until shortly before triggering the explosion. In comparison to explosives, the handling of the individual components of the gas mixture is indeed far less dangerous, since these individually at the most are combustible, but not explosive.
The container envelope receiving the explosive gas mixture for example includes layers of paper and/or plastic.
The flexible container envelopes are designed in a relatively thin and combustible manner and are therefore extremely sensitive with regard to fire and heat. It is ensured in this manner that the container envelope combusts due to the triggered explosion or subsequently to this, in order, where possible, or leave no residues in the boiler space. The combustible design of the container envelope, however, has the disadvantage that this can be damaged or even destroyed even before its filling or before the ignition of the explosion on introduction into the boiler space, on account of the prevailing heat as well as due to the combustion processes.
Inadvertent contact of the container envelope with the hot boiler wall can also lead to damage of this container envelope, apart from the heat and the hot combustion gases in the boiler space.
The container envelopes are wetted with a cooling fluid, in particular water, before or during introduction into the boiler space, in order to prevent this undesirable effect.
This measure, however, is not always sufficient, in order to prevent prior damage or destruction of the container envelope. Despite the wetting of the container envelope, the problem mentioned above particularly exists if the introduction of the container envelope into the boiler space and the placing of this container envelope at the correct location take up a significant amount of time or the container envelope comes into contact with the hot boiler wall, or hot installations such as tube bundles, in the boiler space.